Notifications is a feature that several KDE programs use, even the old Knetworkmanager implements it. Plasma NetworkManagement did not implement it, until now. This weekend I have enabled notifications in Plasma NM. Most of the code is shared with Knetworkmanager, so I did not have to implement that much of code. I have also removed two notifications that did not make much sense since a third notification gives the same information.
Three notifications listed in networkmanagement.notifyrc have never been implemented, which also affects the old Knetworkmanager. After a few hours I finished to implement those three notifications. All notifications seem to be working, so, enjoy :-)
As requested here is a screencast of the notifications working. I added some strings to Plasma NM that have not been translated yet (my desktop is in Brazilian Portuguese), so do not worry about the missing string in the activating notification, it will appear once the string is translated. There are some minor improvements that could be done too.
OBS: I reduced my screen resolution from the original 1600x900 to 800x600 to make the fonts readable.